- ID:
- ivo://nasa.heasarc/skyview/granat
- Title:
- GRANAT/SIGMA Significance
- Short Name:
- GRANAT
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Soviet orbital observatory GRANAT was launched in December 1989 and was operational till November 1998. One of the main instruments of the observatory was the French-Soviet hard X-ray coded mask telescope SIGMA (Paul et al.1 1991, Adv.Space Res., 11, 279). It was the first space telescope that used coded aperture technique for reconstruction of sky images in hard X-rays (35-1300 keV). The angular resolution of the telescope was approximately 12' and the accuracy of a source localization is approximately 2-3'.<p> SIGMA discovered numerous interesting hard X-ray sources including GRS 1758-258, which is located only 40' from bright soft X-ray source GX 5-1. It detected hard X-ray flux from X-ray burster A1742-294, which is very near to bright black hole binary 1E1740.7-2942. SIGMA set an upper limit on the hard X-ray flux of from the central supermassive black hole in our Galaxy.<p> During the period 1990-1998 SIGMA observed more that one quarter of the sky with sensitivity better than 100 mCrab. The Galactic Center region had the deepest exposure ( approximately 9 million sec), with the sensitivity to a source discovery (S/N > ~ 5) or approximately 10 mCrab.<p> A list of all detected sources with references to publications on them is presented in the paper of Revnivtsev et al. 2004, Astr. Lett. v.6. In these survey images (40-100 keV) all performed observations are averaged together. Transient sources that were discovered by SIGMA may not visible in the averaged image. <p> This survey has some features that users should keep in mind. The SIGMA telescope is a complicated instrument and is strongly dominated by the accuracy of the background subtraction. The presence of a very bright source in the field of view of the telescope sometimes cannot be fully accounted for and as a result of it some 'ghost' sources can appear. Such features can be seen in the regions near very bright sources like Crab Nebula, Cyg X-1, Nova Per 1992, Nova Mus 1991, Nova Oph 1993, and in the Galactic Center region. In addition to its nominal field of view (~17x17 deg) located around the optical axis of the telescope, SIGMA had another window of relatively high transparency of its shield, approximately 20-30&#176;; apart from the optical axis. Becuase of this a very bright sources like Cyg X-1 can cause non zero illumination of the SIGMA detector if they are located approximately 20-30&#176;; from the optical axis. The ring-like features caused by this effect, can be seen around Cyg X-1, and Nova Per 1992. <p> The count rate of detected sources (or upper limits) can be roughly translated into mCrab using the fact that that Crab nebula gives the count rate approximately 2.8e<sup>-3</sup> cnts/s in the units, provided in 'flux' maps Provenance: High Energy Astrophysics Department, Space Research Institute, Moscow, Russia; CEA, Centre d'Etudes de Saclay Orme des Merisiers, France; Centre d'Etude Spatiale des Rayonnements, Toulouse, France; F&eacute;d&eacute;ration de Recherche Astroparticule et Cosmologie Universit&eacute; de Paris, France. This is a service of NASA HEASARC.
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- ID:
- ivo://nasa.heasarc/skyview/gtee
- Title:
- GTEE 0035 MHz Radio survey
- Short Name:
- GTEE
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This survey is a mosaic of data taken at the low frequency T-array near Gauribidanur, India. The data was distributed in the NRAO Images from the Radio Sky CD ROM. <p> The original 287x101 tiles had only 1 pixel overlap. To allow higher order resampling, the data were retiled into two hemisphere files of 1726x600 pixels with an overlap of 10 pixels. <p> The southernmost tiles were only 287x100 pixels. We assumed that bottom row of these tiles (as compared with the others) was truncated. Provenance: . This is a service of NASA HEASARC.
- ID:
- ivo://nasa.heasarc/halomaster
- Title:
- HaloSat Master Catalog
- Short Name:
- HALOMASTER
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table records high-level information for the observations obtained with HaloSat and provides access to the HaloSat data archive. HaloSat is the first astrophysics-focused CubeSat funded by NASA's Astrophysics Division (PI P. Kaaret, University of Iowa). HaloSat is designed to map soft X-ray oxygen line emissions across the sky in order to constrain the mass and spatial distribution of hot gas in the Milky Way. HaloSat was launched from the NASA Wallops Flight Facility and delivered to the International Space Station on May 21, 2018. HaloSat was deployed into orbit on July 13, 2018. The spacecraft and science instrument commissioning phase ended on October 16, 2018, and science operations started after that. Initially approved to operate for 12 months, HaloSat successfully collected science data from October 15, 2018, until September 29, 2020, effectively doubling the mission lifetime. HaloSat reentered Earth's atmosphere on January 4, 2021. To trace the Galactic halo, HaloSat is equipped with a non-focusing instrument, comprised of three independent silicon drift detectors (SDD14, SDD38, SDD54) operating in the energy range of 0.4 - 7.0 keV with a field of view of 10 deg in diameter and an energy resolution of 84.8 +/- 2.7 eV at 677 eV and 137.4 +/- 0.9 eV at 5895 eV. The observing strategy was to divide the sky into 333 positions (HaloSat fields) and acquire a minimum of 8000 detector-seconds for each position throughout the initial 12 months of operations. After launch, additional positions were added to the initial 333 positions. HaloSat observations of the chosen fields are divided in intervals of time such that the data files do not exceed 2GB. Each observation is labeled with a sequence number. This database table contains one record for each sequence number and includes parameters related to the observation. The contents of this database table are generated at the HEASARC using information from the data files. The table was last updated in April 2023. This is a service provided by NASA HEASARC .
94. HaloSat Time Log
- ID:
- ivo://nasa.heasarc/halotimelg
- Title:
- HaloSat Time Log
- Short Name:
- HALOTIMELG
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table records the start and stop times of the uninterrupted observation intervals obtained by the three detectors on board of HaloSat and provides access to the HaloSat observations containing these intervals. HaloSat is the first astrophysics-focused CubeSat funded by NASA's Astrophysics Division (PI P. Kaaret, University of Iowa). HaloSat is designed to map soft X-ray oxygen line emissions across the sky in order to constrain the mass and spatial distribution of hot gas in the Milky Way. HaloSat was launched from the NASA Wallops Flight Facility and delivered to the International Space Station on May 21, 2018. HaloSat was deployed into orbit on July 13, 2018 and collected science data from October 15, 2018, until September 29, 2020. HaloSat reentered Earth's atmosphere on January 4, 2021. To trace the Galactic halo, HaloSat is equipped with a non-focusing instrument, comprised of three independent silicon drift detectors (SDD14, SDD38, SDD54) operating in the energy range of 0.4 - 7.0 keV with a field of view of 10 deg in diameter and an energy resolution of 84.8 +/- 2.7 eV at 677 eV and 137.4 +/- 0.9 eV at 5895 eV. The HaloSat data are divided by specific positions in the sky and labeled with a number, the sequence number. Each sequence number contains all data for a specific sky position collected during the HaloSat operations therefore each observation contains time intervals that may be apart day, week or months. This database table instead has in each record the start and stop times of one uninterrupted time interval of good data for a specific detector. This table therefore enables searches of the HaloSat data for a specific time event detected by different obsevatories. The contents of this database table are generated at the HEASARC using information from the data files. The table was created in April 2023. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/skyview/halpha
- Title:
- H-alpha Full Sky Map
- Short Name:
- HAlpha
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The full-sky H-alpha map (6' FWHM resolution) is a composite of the Virginia Tech Spectral line Survey (VTSS) in the north and the Southern H-Alpha Sky Survey Atlas (SHASSA) in the south. Stellar artifacts and bleed trails have been carefully removed from these maps. The Wisconsin H-Alpha Mapper (WHAM) survey provides a stable zero-point over 3/4 of the sky on a one degree scale. This composite map can be used to provide limits on thermal bremsstrahlung (free-free emission) from ionized gas known to contaminate microwave-background data. The map (in Rayleighs; 1R=10<sup>6</sup>/4pi photons/cm<sup>2</sup>/s/sr), an error map, and a bitmask are provided in 8640x4320 Cartesian projections as well as HEALPIX (Nside 256, 512, and 1024) projections on the <a href="https://faun.rc.fas.harvard.edu/dfink/skymaps/halpha/"> H-Alpha Full-Sky Map website</a>. Provenance: . This is a service of NASA HEASARC.
96. HEAO 1A
- ID:
- ivo://nasa.heasarc/skyview/heao1a
- Title:
- HEAO 1A
- Short Name:
- HEAO1A
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- These data were generated at the HEASARC in 1994. Certain gaps and streaks in the image have been fixed by interpolating over the the gap. Typically these gaps are no more than a pixel or two wide. A brief description of the satellite and the data analysis follows. The map used in <i> SkyView </i> is the map designated <tt> 322_15_tot_ecl_samp.img</tt> in the <a href=ftp://legacy.gsfc.nasa.gov/heao1/data/a2/maps/heasarc_med_hed> HEASARC FTP area</a>. Many other maps are available. These differ in epoch, resolution, energy band, coordinate system and projection, and sampling methods. Details are given in the README file in the archive. <p> See Allen, Jahoda, and Whitlock (1994) for full details about the available maps, their processing, and methods for converting the map intensities into familiar physical units. Provenance: NASA, HEASARC. This is a service of NASA HEASARC.
- ID:
- ivo://nasa.heasarc/a4
- Title:
- HEAO 1 A4 Catalog of High-Energy X-Ray Sources
- Short Name:
- A4
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The HEAO 1 A-4 Catalog of High-Energy X-ray Sources represents results from an all-sky survey carried out at high X-ray energies (13-180 keV) from August 1977 until January 1979 using data obtained with the UCSD/MIT Hard X-Ray and Low-Energy Gamma-Ray Instrument on the HEAO 1 satellite. Quantitative results from a model-dependent fitting procedure are given in the form of fitted count rates in four broad energy bands for about 70 sources. The survey is complete, except in regions of source confusion, down to an intensity level of about 1/75 of the Crab Nebula in the 13-80 keV energy band. Forty-four sources were detected in the 40-80 keV energy band, and 14 in the 80-180 keV band. Most of the sources are galactic; seven are extragalactic. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/a2led
- Title:
- HEAO 1 A2 LED Catalog
- Short Name:
- A2LED
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The HEAO 1 A-2 LED Catalog of High-Energy X-ray Sources is the result of a study of the diffuse X-ray sky over the bands of X-ray energies 0.18-0.44 keV and 0.44-2.8 keV from August 1977 until January 1979 using data obtained with the A-2 Low Energy Detector on the HEAO 1 satellite. The HEAO A-2 Experiment was primarily designed for studying the diffuse X-ray background; however, it was also capable of studying point sources to good sensitivity. The detectors surveyed over 95 percent of the sky in the spectral bands listed above to typical limiting sensitivities of 1x10**-11 and 3x10**-11 respectively. Using a significance criterion of 6 sigma for existence, 114 sources are cataloged. The catalog contains a list of all counterpart identifications and a cross-reference to all HEAO 1 A-2 LED team publications on the catalog sources complete through the end of 1981. The identified sources fall into several categories, primarily dependent on observing energy interval. In the 1 KeV band the sources include: 20 galactic stellar sources, 19 extragalactic sources, 13 SNR's, 11 galactic bulge sources, 2 globular cluster sources, and 2 previously reported sources without optical counterparts. In the .25 KeV band the sources include: 24 galactic stellar objects, 12 extragalactic sources, 5 SNR's, 1 bulge source, and 1 globular cluster source. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/a1point
- Title:
- HEAO 1 A1 Lightcurves
- Short Name:
- A1POINT
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- HEAO 1 (High Energy Astronomical Observatory) is a spinning survey mission X-ray satellite. It launched 12 August 1977 and was in operation until 9 January 1979. HEAO-1 rotated once per 30 minutes about the Earth-Sun line. In this manner, the instruments scanned a great circle in the sky that lay 90 degrees from the sun. A given source near the ecliptic was viewed for a few days while sources near the ecliptic pole were scanned nearly continuously during the entire mission. The satellite has limited pointing capability that was used to produce this data, giving continuous coverage of selected sources. The pointings began about 100 days into the mission. The A1 instrument, also known as the NRL Large Area Sky Survey Experiment (LASS) covered the energy range 0.25 to 25.0 keV. The experiment consisted of seven detectors, six mounted on the -Y side of the spacecraft, the seventh on the +Y side. Two detectors, with a FWHM of 1 deg x 0.5 deg and open area of 1350 cm2 were tilted a third of a degree either towards or away from the Z (Sun-pointed) four other -Y side detectors has a FWHM of 1 deg x 4 deg and an open area of 1650 cm2. The single +Y detector has a FWHM of 2 deg x 8 deg and an open area of 1900 cm2. The experiment had sufficient sensitivity to detect sources as faint as as 0.25 uJy at 5 keV for sources with a Crab-like spectrum. Data was collected in either a 5 or a 320 millisecond timing resolution mode: Full sky coverage for both time resolutions was achieved before the mission's end. Wood et al. (1984) discuss the experiment and a catalog of sources in further detail. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/a3
- Title:
- HEAO 1 A3 MC LASS Catalog
- Short Name:
- A3
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table contains information from the HEAO 1 A3 MC LASS Catalog of X-ray Sources. The MC experiment contained two four-grid modulation collimators with an egg-crate collimator with an overall FOV of 4 x 4 degrees (FWHM). The objects in the catalog are possible HEAO 1 A1 sources. The HEAO 1 experiment began on day 224, 19 August 1977 and ended on day 739, 9 January 1979. This is a service provided by NASA HEASARC .
